Electrically heated blanket



April 3, 1962 s. l. RUSSELL, JR

ELECTRICALLY HEATED BLANKET Filed April 6, 1959 Zz-7.2522 for' Smae/ .Zasse/ Jr:

3,628,477 Patented Apr. 3, 196,2

United States Patent @dice 3,028,477 Y ELECTRICALLY HEATED BLANKETSamuel I. Russell, Jr., Glenview, lll., assigner to Northm ern ElectricCompany, Chicago, Ill., a corporationot Delaware p Filed Apr. 6, 1959,Ser. No. 804,272

7 Claims. (Cl. 219-46) This inventidn relates generally to electricblankets, andv more specifically to an improved electric blanket shellincorporated therein, including the method ot' -Wirin it.

gAlthough the principles of the present invention may be included invarious heating appliances,-a particularly usefulapplication is made inelectric blankets and pads. Typical electric blankets comprise a wovencloth` shell having a series of elongated channels woven therein anddened by dividers or stitching. This type of shell is well known in theart, being well illustrated and explained in the United States patent toMoberg, No. 2,203,918. In' the manufacture of electric blankets, aheating wire, having temperature responsive switches located therein, isdisposed in the various .channels of the shell to define a heatedportion. During the manufacture of the blanket, the heating wire iscarried on and unwound from a shuttle which is passed through thevarious channels thereof.

After an electric blanket has been placed in service, it has not beenuncommon for one or more temperature responsive switches therein tocreep in location with respect to the shell. This is particularly trueor aggravated when the user launders the blanket in a manner whicheffects shrinkage thereof. In the rst instance, when the clearance orlooseness provided during manufacture to4 insure that the 'blanket maybe spread out smoothly. However, due to shaking of the blanket,laundering, and the like, and due to the fact that the switches in theshell each havean appreciable weight of greater density than the wireitself, there is a tendency-for the harness to slip with respect to theblanket shell so that the various initial clearances, and so that thevarious further clearances produced by shell shrinkage tend toaccumulate in one place, which place is usually associated with one ofthe switches because of the mass of such switch..V Thus ity has not beenuncommon for a temperature responsive switch to work completely out ofthe channel in which itwas disposed and into the end of the blanketshell. l

lt can be readily understood that when the switch has migrated or creptfrom its desired position, it can no longer sense the temperature atsuch position, and could conceivably even become disposed in van edge ofthe blanket which gets tucked under a mattress.

I havejfound that abetter product can be provided if provision is madefor insuring that the temperature responsive switches are carried by theblanket Vshell in a manner which precludes their drift or migration.Ordinary sewing as 'a mode of anchoring the switches with respect to theharness shell is unsatisfactory since it produces an unsightlyappearance. However, lhave found that the woven stitch or divider can beenlarged to detine a restrictor within the channels where switches areto be located, for such switches to abut against. y

Accordingly, itis an object of the present invention to provide animproved heating'appliance shell adapted to limit the disposition of theswitches.

Another object of the present invention is to provide a shell for anelectric heating appliance wherein the position of the temperatureresponsive switchmay'be limited without sacrifice of a smooth externalappearance'.

A lfurther object of the present invention is to provide a method andmeans of disposing temperatureresponsive switches in a substantiallypermanent position within a shell.

Many otheradvantages, features and additional objects of the presentinvention will become manifest to those versed in the art uponv makingreference to the ldetailed description and the accompanying sheet ofdrawings in which a preferred structural` embodiment incorporating theprinciples of the present invention is shown by way of illustrativeexample.

On the drawings:

FIGURE l is a diagrammatic plan view of an electric heating applianceprovided in accordance with the principles of the present invention;

FlGURE 2 is an enlarged sectional view taken along line ll--ll of FIGUREl; and

FIGURE 3 is an enlarged sectional View taken along line Iil-1ll ofFIGURE l.

As shown on the drawings:

The principles of this invention are particularly useful 1 when embodiedin an electric blanket assembly such as illustrated in FIGURE l,generally indicated by the numeral 10. -The blanket assembly includes ashell 11, such as of woven ,fabric having a heated area generallyindicated by the numeral 12 and dened by `a pair of dividers 13 and 14.The heated area 12 is divided by other dividers )l5-41 to dene aplurality of channels such as 42-68 therein.

The blanket assembly lil also includes an electric harness assemblygenerally indicated by the numeral 69,

and which includes a pairV of main heating wires '76 and 71 disposed inthe various channels 43-67, and a pluralty of temperature responsiveswitches 72-78 disposed in the channels 43, S5, and 67.

The shell ll has a head edge portion 79, and a foot edge portion 8GWhich-are ordinarily placed adjacent to the head and thc foot of the bedrespectively with which the blanket assembly 1G is used.

If desired, the shell 11 may have additional dividers 81 disposed alongthe sides of the heated area 12. The

y purpose of the dividers 81 is primarily, aesthetic in that theyprovide a uniform appearance acrossthe width of the blanket assembly 10.

.The heated area 12 in `the instant embodiment cornprlses in fact twoheated areas, one extending from the divider 13. to the center, and theother extending from the divider 14 to the center. Y

Most of the dividers are of substantially uniform length, and aregenerally alternately staggered so-that the heating wires 70 and 71 maybe looped about the relatively recessed ends as it extends from onechannel to the next.

The harness 69 is provided with a suitable plug assembly 82 by which theharness 69 is connected to a source of electrical power.

As explained above, the shell 11 comprises two layers of cloth which areconjointly woven, the two layers actually being stitched together by aweaving process during their manufacture as explained in the aboveidentified Moberg patent. Thus FIGURE 3 is'scmewhat schematic, andrepresents a typical cross-sectional view across any one of the channels42-68, except for portions indicated by line ll-Il which isschematically shown in FIGURE 2.

For simplicity, each of the dividers shown in FIGURE l has beenrepresented as a mere line. Actualy, it has a finite width, asillustrated in FIGURE 3 by the numerals 15 and 16, an actual blanket-typically having a divider 15 or 16 about one half inchwide each. .Thechannel 43 therefore typically is about one and one-half inches intransverse length, or Width intermediate the dividers 15 and 16. A pieceof yharness Wire 83 connected to a vtemperature responsive switch suchas 7S can easily pass through thelchannel i3 since the typicaltransverse length or width of the switch 78 is one inch. i

To limit the amount which a switch such as 78 can move, I have providedin accordance with Vthe principles of the instant invention arestriction generally indicated by the numeral 84 which in thisembodiment comprises a transverseenlargement ofthe dividers 15 and 16,indicated by the numerals 15a and 16a, and shown in FIGURE 2. In atypical embodiment, the transverse length or width of the channel 43 hasbeen reduced to one-half inch, which size is suliicient to permitshuttling of heating wire therethrough, but which will clearly notpermit the passage of the switch 78 therethrough.

An intermediate harness wire portion. 85 connects the switch 77 to theswitch 78 so that if the harness wire moves in one direction, the switch77 engages an abutment or end 86 of the restriction 84, While if thewire moves in an opposite direction, the switch 78 engages the oppositeend or abutment 87 of the restriction 84.

The length of the restriction 84 is ordinarily not critical, nor is thelength of the wire portion 85, nor is the location of the restriction84. However, jointly these items are critical to this extent that theycoact with each other to insure that the switches 77 and 73 are'disposed with respect to the heated portion 12 of the shell 11 at thedesired point. Further, they are jointly critical so that the switch 7Sand the switch 77 cannot by harness creepage become disposed in the headportion 79 or in the footi portion 80 of the shell 11.

It is apparent that as many restrictors 84 may be provided as isnecessary, the instant embodiment having three such locations. It isalso apparent that a result similar to that shown in FIGURE 2 may beobtained where only one of the dividers 15' or 16 is enlarged by anamountv to effect a corresponding reduction in channel size.

To wire the shell 11, one leg of theheating wire 70 is inserted from theleft' end of the channel 43 and at this time includes the switch 77 andthe intermediate Wire portion 85 which is passed through the restrictor84. The shell is then slid to the left on the Wire portion 85 so thatthe abutment 86 of the restrictor 84 engages the switch 77 and so thatthe end of the wire 85 projects out of the channel 43. The end of thewire 85 is then brought into association with the end ot the wire 83which ends are joined together by the s-witch 78 which is convenientlyinstalled and connected at that time. When the switch '78 is fullyconnected, the shell is smoothed out or debunched to the right, wherebythe switch 78 is drawn into the right end of the channel 43 to assumethe position shown.

The switch 76 is installed ina manner the same as described for theswitch 78. In like manner, the harness leg including the switches 72 and73 is inserted into the left end of the channel 55, after which theswitch 74 is similarly installed. Y Y

The switches 72-78 may comprise any suitable switch element, forexample, of the type taught by Porter in his U.S. Patent No. 2,627,003,disposed and sealed within a suitable water-tight covering. In` thedimensional illustration given above, the dimension of the switch ofcourse refers tothe dimension of the water-tight covering thereof.

By providing the blanket shell 11 with my novel restrictor, means hasbeen provided for limiting the disposition of the temperature responsiveswitch to a desired part of a selected channel.

Although various minor modifications might be suggested by those versedin the art, it should be understood that I wish to embody within thescope of the patent warranted hereon all such embodiments as reasonablyand properly come within the scope of my contribution to the art.

I claim as my invention:

1. In an electric heating appliance shell having a series of laterallyspacedA woven dividers delining a plurality ofV channels for receivingheating Wire including wire having a temperature responsive switch ofenlarged size therein,

Vthe improvement of: a restrictor in one of said channels,

said restrictor comprising a woven part of atleast one of said wovendividers which restrictory is of such size and configuration as toreduce the effective size of one of said channels to' permit freepassage of said wire therethrough, and to preclude `passage of saidAswitch therethrough.

2. In an electric heating appliance shell having a series of laterallyspaced woven dividers delining a plurality of channels forr receivingheating wire including wire having a temperature responsive switch ofenlarged size therein, the improvement of: a restrictor in one of saidchannels, said restrictor comprising a woven lateral enlargement of eachVof a pair of said woven dividers adjacent to each other, theenlargements of said dividers being directed toward and laterally spacedfrom each other by such a distance as to permit free passage of saidwire therebetween, and to preclude passage of said switch therebe-Vtween.

Y3; In an electric heating appliance having a shell, said shell having aseries of laterally spaced woven dividers defining a plurality ofchannels, and a heating wire including wire disposed in one ofk thechannels, the improvel ment of: at least one temperatureVresporisiveswitch convf. Vnected to said Wire, of a size larger thansaid wire, and

shell having a series of laterally spaced dividers Idelining j aplurality of'channels, and a heating wire including Wire disposed in oneof the channels, the improvement of: a pair of temperature responsiveswitches disposed in said one channel, and connected to said wire inseries and spaced from each other by a portion of said wire intermediatesaid switches; and a restrictor comprising a part of at least one ofsaid dividers, which restrictor is disposed between said switches, whichrestrictor is of such size and coniiguration as to reduce the effectivesize of said one of said channels to permit free reception and passageof said Vwire therethrough, and Vto alternatively abut either one ofsaid switches to preclude passage ofV said one switch therethrough.

j 5. In an electric heating appliance having a shell, said shell havinga series of laterally spacedk dividers defining aV plurality ofchannels, and a heating wire includingwire disposed in one of thechannels, the improvement of: a pair of temperature responsive switchesdisposed in said one channel, and connected to vsaidvwire in .series andspaced from each other by a portion of said wire intermediate saidswitches; and a restrictor comprising a part of at least one of saiddividers, which restrictor is disposed between said switches, whichrestrictor is of such size and configuration as to reduce the effectivesize of said one of said channels to permit free reception and passageof said wire therethrough, and to alternatively abut either one of saidswitches to preclude passage of said one switch therethrough; saidrestrictor being of Isuch lengthA and so disposed along the length ofsaid one channel that when one of said switches is in engagementtherewith, the other of said switches is restrained by said wireintermediate said switches to be disposed within said one channel.

6. In an electric heating appliance having a shell, said shell having aseries of laterally spaced dividers dening a plurality of channels, anda heating wire including wire disposed in one of the channels, theimprovement of: a pair of temperature responsive switches disposed insaid one channel, and connected to said Vwire in series and spaced fromeach other by a portion of said wire intermediate said switches; and arestrictor comprising a lateral enlargement of each of a pair of saiddividers adjacent to each other, and disposed between said switches, theenlargements of said dividers being directed toward and laterally spacedfrom each other by such a distance as to permit free passage of saidwire therebetween, and to alternatively abut either one of said switchesto preclude passage of said one switch therebetween; said restrictorbeing of such length and so disposed along the length of said onechannel that when one of said switches is in engagement therewith, theother of said switches is restrained by said wire intermediate saidswitches to be disposed within said one channel.

7. In a method of wiring a channelled shell of an electric heatingappliance where the shell is provided with integral means for limitingswitch disposition within one of the channels of the shell, thesequential steps of: in-

serting a harness leg having a irst temperature responsive' switchintermediate its ends into said one channel from one end thereof so thatthe leading end of the harness leg passes through said limiting means;sliding the shell onto the leading portion of said leg so that one sideof the limiting means abuts said first switch and effects a bunching ofthe shell andthe limiting means on said leading portion intermediatesaid rst switch and the end of said harness leg, and a projecting ofsaid leg end from the other end of said one channel; connecting aharness wire to said leg end by means of a second temperature responsiveswitch in series therewith; and smoothening out the shell to draw saidsecond switch into said other end of said one channel into a positionadjacent to the other side of the limiting means for engagementtherewith.

References Cited in the le of this patent UNITED STATES PATENTS1,994,759 Dermott Mar. 19, 1935 2,203,918 Moberg June 11, 1940 2,393,182Newell Jan. 15, 1946 2,403,803 Kearsley July 9, 1946 2,421,953MacKendrick lune 10, 1947 2,432,785 Moberg Dec. 16, 1947 2,518,147Johnson et al. Aug. 8, 1950 2,802,091 MacKendrick Aug. 6, 195.7

FOREIGN PATENTS 605,666 Great Britain July 28, 1948

